Rustler, if your satisfied with your current power amp, I want you to look at the addition of a preamp as talorying the sound to your liking, bringing out the best qualities from your power amp, both complementing each other. Some power amps need the drive to sound their best. A direct connection sometimes can prove to be very trying in the long run, not very musical. If this direct connection can be proven to be true as more desirable then all of us need to dispense with the preamp and you might build your system around something that only you might like. If you can figure out a way to dispense with the power amp then I need to get a new hobby. |
Autoformers control the cable by optimizing the impedance relationship as one attenuates the signal. And most systems, even phono, don't need gain.
A fair amount of care must be used, however, in matching sources and amplifiers (the coupling capacitor mentioned above). |
Yes! Well, it took a design expert, but finally a great answer. Driving the inter-connect cable---what a concept! Maybe another reason why the sound of any given cable is so system-dependent---it's interacting with the volume control in the pre-amp of every system it's put in. |
A preamp line section has 4 functions:
1) control volume
2) select an input
3) add any needed gain
4) control the interconnect cable
The two latter functions are not done by passive controls of any sort. That 4th function is also poorly understood, not only by audiophiles but designers too. Often if you have a digital source, you may not need the gain and so a passive might seem attractive. But the interconnect cable will be far more critical with a passive control.
Quite often if a passive is involved, people report a loss of bass impact and overall dynamics as the volume control is reduced in level from full on. This is likely due to the source having some sort of coupling capacitor at its output, which is then in series with the control. Unfortunately, the Red Book specification for CD demands that the output of the CDP or DAC be high, in fact so high that it can clip all known amplifiers if the signal is not somehow reduced. So a volume control is essential.
Now if you don't need the gain, the obvious solution is a buffered volume control. This is essentially a volume control with some sort of follower circuit (either tube or solid state) that has no gain but does isolate the control from the interconnect cable. This allows for vastly reduced coloration due to the interaction of the volume control and the cable.
Since I listen mostly to LPs, a buffered control in my system is insufficient as the extra gain is handy! But if you plan to play only digital the buffered volume control is your best bet if you don't go with an active line section. |
Ralph should be along shortly selling his point of view.
I mean products. Like always; never miss the opportunity.
Sorry |
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A P.S. to my previous post: If you do eventually have an opportunity to try a tube (or other) preamp in your system, and if you find the resulting sonics to be preferable to no preamp, keep in mind the possibility that the root cause MIGHT be a less than optimal tonal match between your power amp and your speakers. Particularly in view of the impedance characteristics of the speakers (4 ohms nominal, 0.8 ohms at 20 kHz), which could conceivably result in an over-emphasis of the upper treble in conjunction with some solid state amplifiers.
Should that ever prove to be the case, changing power amps would probably be a better solution than adding a preamp.
And if there is any uncertainty in that regard, researching reported user experiences involving the use of Spectron amps with Martin Logan speakers may be helpful.
Regards,
-- Al
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The burden of proof should always be on adding anything to the signal path that is not an obvious necessity. In this specific case a preamp is not an obvious necessity, and per George's analysis (with which I agree) the odds appear to be in favor of that burden not being met. However, as others have indicated the only way to know for sure is to try it.
Good luck. Regards,
-- Al
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A great preamp is the heart of a great system. |
I submit the answer depends on the components involved. I had a PS Audio DSD DAC and compared to the Parasound JC2 preamp, I initially preferred the DSD direct. After extended listening I felt I lost dynamics and detail. I sold the DSD and Parasound JC2 to purchase a Bricasti M1 DAC. In my system the Bricasti was a definite improvement over the DSD. The dynamics were there, detail, but I still felt like something was missing. I went from the Bricasti M1 directly into my Jeff Rowland 525, to the M1 going into the Jeff Rowland Continuum S2 integrated. It sounds better than ever. I don't know if it's because the amp section of the Continuum is that much better, the added preamp section, or a combination of both. I prefer music with a preamp. |
Hi Rustler.
Your PS Dac has from it's single ended output has 100ohms output impedance at 2.8v from it's "Resolution perfect volume and balance controls"
Your Spectron amp has 50kohm input impedance at 26db of gain.
These are a perfect match for each other to go direct with, and will give you the best transparent/dynamic sound you can get.
By putting a preamp into the mix you are just throwing money away to colour the sound with.
Cheers George
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All true Phusis, but the OP was asking specifically about adding a separate (perhaps tube) pre-amp between both his DAC & phono stage and his power amp. |
Like many people, I tried to save money and eliminate the preamp. If you're happy with what you hear without it, then good for you. Ultimately I opted for a preamp. I can't remember which Sterophile writer said that "the preamplifier is the beating heart of a system" I fully agree. I'm using a Classe CP700. I can't imagine doing without it. |
I also use a Spectron Musician ii high current power amp to drive Martin Logan Spires. |
Thanks for asking, George. I have the PS Audio DirectStream DAC and their Memory Transport CD unit. I also have their Phono converter phono section. I really appreciate the help; I'm not really close to any place where it's easy to audition stuff, so all the advance advice I get is greatly appreciated. |
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Andrew9405, you crack me up!
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09-22-15: Bdp24
Having enough gain in a source component is not all that is necessary to get the best sound out of that component. The output stage of a good pre-amp is engineered to drive the input stage of a power amp, while any given DAC or phono stage may or may not be.
In a related topic, it is for the same reason that many listeners (no pun intended---see below ;-) find the sound of a passive pre-"amp" to lack something (see Art Dudley's column in the current Stereophile). However, over these last years dedicated DAC/preamps have arisen that are neither comparable to stand-alone DAC's in the traditional sense nor passive preamps; instead their purpose being precisely to act as preamps in addition to being DAC's, and hereby successfully driving a power amp on their own - as a singular component. Not only are they effective in doing this, but they also rid you of extra sets of power cables and IC's with shorter signal paths to boot. Indeed this discussion seems to have become somewhat dated in light of the development in this field for some time now. |
Rustler hi,
Please list your models of source and poweramp so we can let you know if you have a good impedance match to give you the best (most transparent/dynamic) sound.
Cheers George
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Totally depends on what type of equipment the respondent(s) sell here.
They'll be along shortly................ |
Having enough gain in a source component is not all that is necessary to get the best sound out of that component. The output stage of a good pre-amp is engineered to drive the input stage of a power amp, while any given DAC or phono stage may or may not be.
In a related topic, it is for the same reason that many listeners (no pun intended---see below ;-) find the sound of a passive pre-"amp" to lack something (see Art Dudley's column in the current Stereophile). |
The answer is ... it depends.
A good pre-amp will add a distinctive sound of its own. You'd have to try one and compare to not using one to know for sure which sounds better to you. |
It really depends on the quality of the volume control. According to many, analog volume controls using sound better in most systems. Passives too, but the gain issue then comes into play for many.
IMHE, usually an active preamp with analog volume sounds best to most ears. A good tube preamp like the Cary SLP05, Modwright, Backert Labs, Audio Research, Herron, BAT..many options all are good choices.
You can try a cheap pair of passive attenuators for an idea of passisves in your rig. Of course, I'd borrow/demo a preamp first if possible. Cheers,
Spencer |
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